in·vo·lu·tion / ˌinvəˈloōshən/ • n. 1. Physiol. the shrinkage of an organ in old age or when inactive, e.g., of the uterus after childbirth.2. Math. a function, transformation, or operator that is equal to its inverse, i.e., which gives the identity when applied to itself.3. formal the process of involving or complicating, or the state of being involved or complicated: periods of artistic involution.DERIVATIVES: in·vo·lu·tion·al / -shənl/ adj.in·vo·lu·tion·ar·y / -ˌnerē/ adj.

involution (in-vŏ-loo-shŏn) n.
1. the shrinking of the uterus to its normal size after childbirth.

2. degeneration of the corpus luteum, which occurs after pregnancy or if implantation of the embryo fails.

3. atrophy of an organ in old age.
—involutional (in-vŏ-loo-shŏn-ăl) adj.

involution (festooning) Contorted bedding in the near-surface zone of unconsolidated earth material or bedrock. Deformation may be regular, producing festoon-like features (e.g. ‘frost boils’), or highly irregular, showing pronounced distortion and twisting. Involution is characteristic of past and present periglacial zones, and is due basically to ground freezing.

involution
1. A decrease in the size of an organ or the body. It may be associated with functional decline, as occurs in the ageing process, or follow enlargement, as when the uterus returns to its normal size after pregnancy.

2. The turning or rolling inwards of cells that occurs during the development of some vertebrate embryos.